How to store enemies spawn schedule for each scene ?

Hi all,

I am creating a zombies shooting game, and this game has 10 kind of zombies , such as: zombie1 ,zombie2 ,…zombie10 .
I want that each scene, GameController create 5 zombies and those zombies are created in a schedule (in order) such as:

scene 1: zombie1, zombie1, zombie2, zombie5, zombie5

scene 2: zombie2, zombie1, zombie2, zombie7, zombie7

scene 2: zombie2, zombie2, zombie2, zombie7, zombie7

I saw “plants vs zombies” can spawn zombies right time and in order but I do not know how to do.

The question is that,

How they do it ?

How can I save those schedules ?

Are there any kind data-structures to save those schedules ?

Thank everyone.

You could just put a gameobject with a ‘spawnenemies’ script on it in each scene that spawns the correct enemies?